(CNN) -- Former Massachusetts Gov. Mitt Romney and former Arkansas Gov. Mike Huckabee appeared to be competing closely for votes among Republican voters who describe themselves as "conservative," according to early exit polls of voters in the 15 states across the country with Republican primaries Tuesday.

About 80 percent of Romney voters described themselves as "conservative," while 75 percent of Huckabee voters described themselves as "conservative," the initial exit polls showed.

Less than half -- 49 percent -- of those who said they voted for Arizona Sen. John McCain described themselves as "conservative," the exit polls showed.

For Democrats, early exit polls showed that Sen. Hillary Clinton of New York and Sen. Barack Obama of Illinois were nearly splitting voters who had decided who to vote for in the last three days.

About 47 percent of those voters said they had picked Obama, versus 46 percent who said they had voted for Clinton.

Though close, the exit polls suggested that the Democratic base is not bitterly divided over its choice.

Nearly two-thirds -- 72 percent -- of Democratic voters said they'd be satisfied with Clinton as the nominee, and 71 percent said they'd be happy with Obama.

The early exit polls also showed that Obama's campaign message, which centered on "change," resonated among people who voted for him. Nearly three-quarters -- 74 percent -- of Obama voters named "change" as the top quality they were looking for in a candidate, while 11 percent said they were looking for a candidate who "cares about people." Only 3 percent of Obama voters said they were looking for a candidate with experience.

Experience appeared to be more important among Clinton voters, with 45 percent naming that as the top quality in a candidate. Just 29 percent of Clinton voters said they were looking for a candidate who would offer "change," and 15 percent said they were looking for a candidate who "cares about people." See the qualities that voters were seeking »

Because of time zone differences, the exit polls reflect voters in the eastern and central parts of the country at a disproportionately high level. The results will be updated throughout the night with additional surveys from across the country.